Electrical protective apparatus.



' F.B.OOOK. ELECTRICAL PROTECTIVE APPARATUS. APPLICATION FILED JULY 15. 1909.

y MM Q 3) ATTORNEY.

FRANK B. COOK, F CHICAGO, ILLINOIS.

nnnernroan rsornorrvn APPARATUS.

Specification of Letters latent.

Patented Aug. 9, 191%.

Application filed July 15, 1909. Serial No. 507,772.

T 0 all whom it may concern:

.Be'it. known that .l, FRANK. B. Cook, a. citizen of the lmted States of America, re-

siding at Chicago, in the county of Cook and State of lllinois, have invented new and useful l llcctrical Protective Apparatus, of which the following is a specification, reference being bad to the accompanying drawings, illustrating,- sumo.

My invention relates to electrical protective apparatus and in particular to telephone switchboard protectors.

The principal objects of my invention are, to provide improved protective apparatus of the cl'iaractcr hereinafter specified; to provide an improved telephone switchboard protector embodying electrothermal protectors, fuses and lightning arr-esters; and to provide an improved electrothermal protector for such apparatus.

@ther objects will be apparent'from the following specification.

In the accompanying drawings illustrah ing the preferred form or" my invention, Figure 1 is a plan view of a bank of protective apps 'atus constructed in accordance with this lDYCDtlOIZ I and Fig. '2 is a cross-sectional view of the clectrothermal protector and l'ghtning arrester used in the apparatus of Fig. 1, with portions shown in elevation.

In some instances it is very desirable to have fuses in connection with heat coils and lightning arresters at a central telephone exchange, for protecting the lines of the system, without having; the :t'uses on a separate rack from the other protectins and thereby necessitating considerable extra wiring and expense, With this particular object in view l have provided the protective apparatus shown in the drawings, in which the incloscd fuses are associated Willi the heat coils and lightning arresters in such a manner that no extrav :tusc rack or wiring is re quircd :tor acconnnodating the fuses or connecting the several protective devices as protectors tor the various circuits. In addition to this i have provided in this invention an embodiment of protective apparatus in which the fuses, lectrothcrmal protectors and lightning arr-esters constitute a single piece of apparatus. adapted to be mounted on a cross-connecting rack in banks in a manner well understood. These banks of the complete apparatus may be added to the cross-conneciing rack as desired, the exchange grows, to r :comniodate the increased number of lines. It will be readily seen that such a protector greatly'simplifies the apparatus and the wiring of such systems.

By reference to the aecompanyingdrawings, 1 is a mounting plate on which are mounted spring members 2 9., 3 3, l l, 5 5, 6 (3 and T 7, preferably as shown, the spring ,members 5 5 being electrically connected with metallic strips 8 S which terminate at the rear of the bank of protectors in switchboard terminals 9 and 10. Of course it will be readily understood that any number of pairs of the protective apparatus shown may be mounted on a. single mounting plate 1. Spring members i and 5, on each side of the plate 1, are preferably soldered together at 11 so that they make electrical connection with each other. Spring members 17 17 terminate atthe rear of the plate 1' in line terminals 12 and 13, preferably as shown. Spring members J: make electrical connection with spring members 3 3, respecdvely. Spring members 2 and 8, on each side of the plate 1, lie in the same plane so that they *an be readily operated and made to contact the corresponding strip lat of the plate 1, by aninsulating bushing 15 which is operated by the corresponding spring 5 when the corresponding electrothermalprotector 16 gives way in a manner hereinafter described.

Enclosed fuses 1T 17 are held in place by spring members 6 7, 6 7, respectively, in a manner Well understood. These fuses 1T 1.7 are preferably of: the noninflammable type. It will readily be seen that the fuses 1'? 17 may be removed as desired, by simply forcing the for ard ends of same out away from the platel.

The lightning arrcsters 18.18, each comprising a pair of carbon disks with a suitable dielectric interposed t-herebetween, are mounted between springs; at, respectively, and the mounting plate 1, preferably as shown, the inner carbon of; each arrester preferably fitting into a semicircular notch, as 19, in the corresponding strip 14, which holds the arr-ester against lateral displacement. is held in place by a disk 21 having a projeeting end portion 2 thereon extending into the carbon and insulated from the inner carbon by an insulating bushing 23 which extends through a hole in the carbons shown in Fig. 2. Each spring a tits into an annular groove formed by the disk 21 and the annular'projection 2% of'the pin loo The outer carbon 20 of each arrester 25 which extends out from the disk 21, the

said springs at 4 bearing inwardly against the disks 21 21 to securely hold the lightning arresters in place. The mounting plate 1 is preferably grounded to provide a ground connection for the li htning arresters 18 18.

The electrothermaf protector 16 comprises a spool 26 soldered on the outer end of the pin 25' by an easily-fusible solder, an external metal shell 27, and a resistance filler 28 between the spool 26 andthe shell 27, the

. ends of the shell 27 being. formed over as at protector, and the spring 4 makes elcca 29 to tightly compress the resistance material 28 soas to keep saine of the desired resistance. The shell 27 is insulated from the spool 26 by mica disks 31 31 placed against the outside ends of the spool .26 before the shell 27 is finally formed over. The ends of the spool 26 are preferably made hexagonal in form so as to prevent turning disks 31 is dropped into the shell 27-, then the spool 26 is dropped into the shell 27 on top of the mica disk 31, then the. comminuted resistance material 28 is packed into the shell 27 around the spool 26, then the other mica disk 31 is dropped into the open end of the shell 27 on top of the spool 26,,

and finally the open end of the sliell 27.is

formed over as shown at 29, as much as is I desired, ,to properly adjust the resistance .through the whole and firmly hold the parts together x i'ts th'e spring iiiakeselectriealconnectioirwitlrthc shell 27 of the electrotherinal trical connection with the pin 25-, as clearly shown in Fig. 1, it will readily be seen that the circuit through a set of the protective" apparatus, oneither side of the plate 1, ex-

tends from a line terminal 12 (01".13')" through spring 7, iiiclosed fuse 17,,spring (3, connection 11, spring 4, pin- 25, spool .26,

"resistance material 28, shell 27, spring 5, and .termina'l strip 8 to switchboard terminal 10 (or-9). lVhen an abnormally large current- (generally termed a sneak current) trav- ,erses-this circuit it produces heat in the re sistance material 28, which heat softens the easilyfusiblesolder, between the spool-2l and the pin 25 and thereby permits the heat ing element 16 as a whole to be sl d,loiigitudinally along the 311125 as desired. Now

tlie'spring' 5 slides th limiting element 16 as of Fig.1. i The purpose and operat'ion' of the fuses 1'7 lT-and lightning arresters' 18. 18am: be

lieved to be well understood withoutfurther description The fuses, however,- in this apa whole, on the pin 25 toward the mounting plate 1 to approximately the position shown on the right of Fig. 1, the spring 5 in its operation engaging the corresponding insulating bushing 15 and causing same to bear the corresponding springs 2 and 3 into contact with the corresponding metal strip 1 1 ofthe ground plate 1, thus grounding the spring 4 which is connected through the corresponding inclosed fuse 17 to the line,and also grounding the corresponding spring 2 which may be connected with a suitable alarm in a manner well understood. v

Each of the springs 5 5 is provided with a leg 30 thereon adapted to engage the outer endof the corresponding pin 25, if desired,

to ground also the switchboardspring 5, :through spring 4 and'the-corresponding pin .25, Inthe drawings, however,'the spring 5 and the leg 30 thereon, on the right of Fig. 1, are shown out ofzcont-act with the electrothermal protectorle andgth'e' pin 25, after the. protector 1(3 has .been operated, thus maintaining the cir'cuit to the switchboard o -ienat'ter the operationof the protector 16.

This condition is obtained by simply adjusting. the parts so that the resiliency of the springmembers 2', 3"and 5 causes the switchboard spring 5 to spring back slightly away .troin the heating element 16 and pin '25, .afterits sudden movement toward the mounting;plate 1 in operating the heating element 16 on thepin If, however, it is desired. to ground the switchboard spring 5 when the line spring 4' is grounded, the leg 30 of the-spring 5 is adjusted so that it will reinainfin contact with the pin 25 after the electro'thermalprotector has been operated.

Thus it will be seen tliatwith this construction and arrangement, the switchboard spring may be either grounded or. disconnected froin t heline, upon the operation of theelectrotheiinal protector, whicheveris desired. tector for another operation, it'is only necessary to reheatthe easily-fusible solder between the'sp ool2l'i and the pin ,25, in any. suitable fiiianiieif, slide the heating 'eleiiient 16-asa .whole back to the outer end of thet.

pin 25, and theiuperniit the easily-fusible solder to cool whereupon the apparatus. will To. reset theelectrotherinal. pro-- be resettoif operation as shown on the left paratus are prefcral'ily made. to carry considerable more current than thati-e uirei1 to 010011110. the electrotlieruial protectors,and

'a're intended-toblow to protect the switchboard. circuits f -kmi only heavy currents" -.lVhen is desired to remove a-lightniug ai rester l8 and the corresponding electrot'li' ei-ui:il. protector "from the apparatus, it-is appended claims.

scenes only necessary to force same from the grasp t the corresponding spring 4, in a manner well nderstood.

I do not Wish to limit this invention to all one particular details herein set \torth, as

rions modifications of same may no made "washout departing from the scope of the lihat 1 claim as my invention is-z i. i protector of the character described sing a mounting plate, a series of sets members mounted along the said said plate near the trunt edge tnerct o some of the said spring members, a of ciectrothernnil protectors mounted along the said plate near the front edge thereof, by some of the said spring members, a o't' incloscd fuses mounted along the said plate 'by some of the said spring mcmhers, to the rear of the said electrothermal protectors and lightning arresters, and suitable line and switchboard terminals at the rear edge of the said plate connected with the said protective devices, all for purposes substantially as described.

9. l'illcetric l protective apparatus of the character described comprising a mounting plate, a plurai y of mountings on the said each m t-ing having a plurality of men'ib 's mounted thereby, an elecral protector and lightning arc, rried by the spring members of one mounting, a is her of each of the said moul'itiugs, and electrical connections extending "from the electrothermiii-protector mounting to the other mounting whereby both line and switchboard terminals for the protective devices located in close proximity to each other.

Electrical protective apparatus of the character described comprising a ground plate, a. pair o1 mountings on the said plate, 'd mountings having spring members n'munted on the said plate thereby, an electrothermal protector and a lightning arrester carried by the spring members of one of the said mountings. a tusecarried by a spring member of each of the said mountings, and an electrical connection extending from one of the said mountings to the other, for pnrposes substantially as set forth.

at. Electrical protective apparatus of the character described comprising a mounting plate, a series of spring members mounted along the said plate and suitably insulated from eachother, a series of lightning arresters mounted along the said platenear the forward edge thereof, a series of electrothermal protectors mounted along-the said plate in the vicinity of the said arresters, a series of inclosed fuses mounted along the said plate to the rear of the said electrothermal protectors and lightning arresters, the said spring members being arranged to connect;

se carried by a spring mem 'ies of lightning arresters monntedelectrothermal protectors, and the said light ningarresters as third-legs to the respective said series circuits, and electr'cal connections whereby the various terminals for the said protectors are all located in the same vicinity.

Electrical protective apparatus of the character described comprising a mounting plate having a plurality of mountings thereon, some located medially regarding the said plate and others located near the rear edge of the said plate, ich of the said mountings having spring members mounted thereby and insulated from each other, lightning arresters and electrothermal protectors carried by the said spring membersnear the for- Ward edge of the said plate, means for causing the suitable switching of the various circuits upon the operation of the electrothermal protectors, inclosed fuses carried by the said spring members and extending substantially from the said medial mountings to the said rear mountings, the said fuses being conneeted in series with the respective electrotl'iermal protectors, and the lightning arrosters being connected as third-legs to the said respective series connections, the said 't'uscs having line terminals in the vicinity of the said rear mountings, and electrical connections extending from the said medial mounting to the said rear mountings, under: neath the respective fuses, whereby switchboard terminals for the pparatus are provided in the vicinity of the said rear mountings and line terminals, substantially as described. v

6. An electrothermal protector comprising a spool and an outer metallic-musing therefor suitably insulated from each other, comminuted resistance material. held under compression between the said spool and outer casing, a stationary pin soldered through the said spool by easily-fusible solder, and means for automatically nmving the said spool, resistance material and easing as a unit, relatively to the said pin upon an abnormally large current in the protector, for purposes substantially as described.

7. An electrothermal protector comprising a stationary pin, and a heating element movable rclatfmly thereto upon abnormal hiating, and normally secured thereto by heatsusceptiblo material, the said heating element comprising a spool, an outer shell, insulatii'igdislis at the. ends of the spool insulating same from the said shell, and comminuted resistance material between the said spool and shell, the latter being formed over at the ends whereby the said resistance material is held under pressure.

8. A heating element for an electrotherimil protector comprising inner an d outer metallic members providing an annular space therebetnvecn and insulated from each other, and comminutcd resistance material within the said annular soace, the said outermetallic member being iormed over whereby the said resistance material is'held under pressure.

9. A. heating element for an electrothermalprotector, comprising-inner and outer metallic members, one surrounding the other and insulated therefrom, and resistance over at its ends against the said mica disks whereby the parts of the device are substantially held together.

11. In electrical protective apparatus, a lightning arrester comprising'a pair of circular disks having a suitable dielectric therebctween, a metallic disk bearing against one.

of the saidilightning-arrester disks and having an inwardly-projecting pin and an outwardly-projecting pin integral therewith, the said inwardly-projecting pin projecting into one of the said light-ning-arrester disks, a spring memberbearing' againstthe said metallic disk to hold the lightning arrester. in place, an electrothermal heating element encircling the aid outwardly-projecting pin and normally secured thereto by heat-susceptible material, and a second: spring member bearing against the said heating element whereby the latter is moved longitudinally on'the said pin upon an abnormally large current in the said heating element, sub- I stantially as described.

12. In electrical protective apparatus of the character described, a mounting plate, a

pair of spring members mounted on the said plate, a stationary pin positioned by one of ceases the said spring members and in electrical contact therewith, an electrothermal heating element carried by the said pin and normall secured thereto by heat-susceptible materia one of the said spring members of the pair normally bearing against the said heating element to move same longitudinally on the said pin upon an abnormally large current in the device, and means for groundingthe first-mentioned spring member of the pair upon the operation of the apparatus, the second-mentioned spring member of the pair having a portion thereon adapted to engage the said pin upon the operation of the apparatus, to ground the said second spring member of'the pair, through the said pm. i

13. In electrical protective apparatus of the character described, a mounting late, a pair of spring members mounted on t e said plate, a stationary pin positioned by one of thesaid spring members and in electrical contact therewith, and an ,electrothermal heating element encircling the said pin and normally secured theretoby heat-susceptible material, one of the said spring members of the pair normally bearing against/the said.

heating element to move same longitudinally on the sid pin upon an abnormally'large current in the device, the resiliency of the latter said spring member causing it to recede from the said heating element after the operation of the latter, whereby the circuit through the device is opened. 4 v

14. A heating element for an electrothermal device, comprising inner and outer metallic members providing an annular space therebetween, and comminuted resistance material within the said annular space and contacting the said metallicmembers.

As inventor of the foregoing I hereunto subscribe my name, this 10th ay of 'J uly, 190a- FRANK n. coon.

Witnesses:

FREDERICK R. Panama, MAUDE J. BArah-fl 

